In the last hours of Mutassim Gadhafi's life, he appeared scornful and defiant of his rebel captors and called them "petty" and "small."
Mutassim, son of the late Libyan dictator Moammar Gadhafi, is seen in a recently released video injured but sitting quietly as one of the rebels mocks him just hours before his death last week.
"It's over for you. How the mighty have fallen," the man says in Arabic. "The world will be watching you wounded..."
Mutassim then answers the rebels, saying, "My wounds are badges of honor."
After the rebels demand Mutassim speak into the camera, Mutassim stares up at one of his captors and asks "How petty are you?" and then demands to know his name.
"You're so small," Mutassim says after the man answers.
"Just wait and see, you dog, just wait and see," the man says.
The new video appears to have been shot around the same time as a series of videos which surfaced online Friday showing Mutassim in the same clothes calmly smoking a cigarette and drinking water. A separate video showed the same man apparently dead with a distinct wound at the base of his neck that was not visible in previous videos.
Mutassim and Moammar Gadhafi were killed last week but only buried today at a secret location, officials with Libya's National Transitional Council told reporters.
The separate videos showing Mutassim and Moammar Gadhafi appearing very much alive and in captivity spread through social media sites in recent days and have spurred international calls for investigations into the Gadhafis' subsequent deaths. Rebels had originally claimed Moammar Gadhafi had been killed in "crossfire."
"On the issue of Gadhafi's death... the circumstances are unclear -- there seem to be four or five different versions of how he died," the U.N.'s High Commission for Human Rights said in a statement last week. "We believe there is a need for an investigation and more details are needed to ascertain whether he was killed in the fighting or after his capture."
The National Transitional Council said Monday they would launch an investigation.
According to a series of confidential U.S. State Department cables leaked by the website WikiLeaks, before the popular revolt began in February Mutassim, the country's national security advisor, was seen as an ambitious son who aspired to succeed his father, even though there was widespread belief Mutassim's brother Saif al-Islam would be the country's next leader.
Saif al-Islam is currently the only member of Moammar Gadhafi's immediate family that is unaccounted for, though several press reports suggested he may still be in Libya but fleeing to Niger where his brother, Saadi, took refuge last month.
A Syrian news station carried a message it said was from Saif al-Islam Saturday in which the missing son said, "I'm in Libya, alive, free and intend to go to the very end and exact revenge. I say go to hell, you rats and NATO behind you."
The other Gadhafi children were either killed during the revolt or managed to escape Libya for Algeria before the rebels closed in on the notorious patriarch.
The Associated Press contributed to this report.